Definition
FIDO2, also known as WebAuthn, is an open authentication standard that enables passwordless logins for web and mobile applications. It allows users to authenticate using strong, phishing-resistant methods like biometrics or hardware security keys instead of traditional passwords. FIDO2 works by establishing a secure, encrypted channel between the user's device and the service they are trying to access, verifying their identity without transmitting sensitive credentials. This significantly enhances security by preventing credential stuffing attacks and man-in-the-middle exploits, making it crucial for protecting user accounts and sensitive data. For instance, using a fingerprint scanner on your phone to log into a banking app is a common FIDO2 implementation. Unlike multi-factor authentication which often relies on something you know (password) plus something you have (phone), FIDO2 aims to replace the 'something you know' entirely with a more secure, device-bound credential. You will encounter FIDO2 concepts on security certifications like CompTIA Security+ and CISSP.